The present invention relates to a subscriber interface control method of controlling a plurality of subscriber interface sections and monitoring their operation states.
A communication system having an interface with subscribers generally includes a plurality of subscriber interface sections such as a plurality of line circuits. One subscriber interface control section controls the operations of these subscriber interface sections and monitors their operation states. In such a case, with an increase in the number of subscriber interface sections, the number of control signal lines from the control section to the subscriber interface sections increases. For this reason, the control section is connected to the respective subscriber interface sections via one control signal line. The control section controls the subscriber interface sections and monitors their operation states via this control signal line.
FIG. 4 shows a conventional arrangement of such a communication system. Referring to FIG. 4, reference numeral 1 denotes a subscriber interface control section; 2, a control/monitor signal line made of one line; and 3.sub.1 and 3.sub.2, subscriber interface sections.
When the accommodation locations of the subscriber interface sections 3.sub.1 and 3.sub.2 are determined, accommodation location numbers a unique to the respective subscriber interface sections and corresponding to the accommodation locations are automatically set. The subscriber interface control section 1 controls the subscriber interface sections 3.sub.1 and 3.sub.2 in accordance with these set accommodation location numbers a.
The subscriber interface control section 1 sends the accommodation location number a corresponding to the subscriber interface section to be controlled and control instruction data to the control/monitor signal line 2. These accommodation location numbers a are different numbers unique to the respective subscriber interface sections. Of the subscriber interface sections, only the subscriber interface section corresponding to this accommodation location number a receives the control instruction data following the accommodation location number a. As a result, the corresponding subscriber interface section is set in the operation state based on this instruction.
Assume that a control instruction is sent from the subscriber interface control section 1 to the interface section 3.sub.1 whose accommodation location number a is "1". In this case, only the interface section 3.sub.1 whose accommodation location number a is "1" is subjected to operation state control, but the interface section 3.sub.2 whose accommodation location number a is "2" is not subjected to control. The interface section 3.sub.1 having undergone control is set in the operation state based on this control, and returns information about the control result to the subscriber interface control section 1 via the control/monitor signal line 2. As a result, the subscriber interface control section 1 can recognize whether normal control is performed on the interface section 3.sub.1 side. Note that the subscriber interface control section 1 performs a warning output operation or the like upon determining, on the basis of the above return information, that abnormal control is performed on the interface section 3.sub.1 side.
The same applies to a case wherein the subscriber interface control section 1 monitors the operation state of a subscriber interface section 3. More specifically, the subscriber interface control section 1 sends the accommodation location number a corresponding to the subscriber interface section to be monitored and a monitor instruction to the control/monitor signal line 2. In this case, only the subscriber interface section whose accommodation location number coincides with the received accommodation location number returns operation state information based on the received monitor instruction to the subscriber interface control section 1 via the control/monitor signal line 2. The subscriber interface control section 1 can therefore recognize the operation state of the corresponding subscriber interface section on the basis of the return information.
Assume that a monitor instruction is sent from the subscriber interface control section 1 to the interface section 3.sub.1 whose accommodation location number a is "1". In this case, only the interface section 3.sub.1 whose accommodation location number a is "1" receives the monitor instruction, but the interface section 3.sub.2 whose accommodation location number a is "2" receives no monitor instruction. The interface section 3.sub.1, which has received the monitor instruction, returns information about the operation state to the subscriber interface control section 1. The subscriber interface control section 1 performs a warning output operation or the like upon determining, on the basis of this return information, that the operation state of the interface section 3.sub.1 is abnormal.
As described above, the subscriber interface control section controls the subscriber interface sections and monitors their operation states in accordance with the accommodation location numbers unique to the subscriber interface sections. If the accommodation location of a given subscriber interface section changes for some reason, the accommodation location number of the subscriber interface section is automatically changed. The subscriber interface control section cannot therefore control this subscriber interface section by using the old number. For this reason, every time the accommodation location of a given subscriber interface section changes, the subscriber interface control section must change the control/monitor designation number for controlling and monitoring the given subscriber interface section. In addition, the subscriber interface control section must perform control and monitor operations for the subscriber interface section again and recognize the operation result. The change/setting of a control/monitor designation number, confirmation of an operation state by the system after the changing/setting operation, and the like are cumbersome operations.